The question was of a theoretical drive system, not any known to man. As for the fusion drive proposed: That's ridiculous. You'd need pure fusion bombs if you wanted that to work, plus you can't contain a nuclear explosion using magnetics. Also, small H-bomb is an oxymoron. The whole point of a thermonuclear weapon is a bigger boom. Lastly, plutonium is only useful as part of a bomb, it wouldn't be used in a nuclear drive.

Whoa, cowboy. He's an economist, not a nuclear physicist. On top of that, translating German (a hard language) into English (another hard language) ain't easy. Not that you're wrong, just go a bit easier on the guy.

Ekkehard: Cadet's right about the size of a fusion explosion. They're stinkin' huge. There's no such thing as a small nuclear explosion, either for fusion or fission. Oh, and Plutonium burns on contact with air, which is why Uranium is much more common in weaponry (it doesn't).

I don't see how Herr Merbold's drive would work: in order to have a fusion bomb, you have to start the whole thing off by detonating a fission bomb which itself has a certain minimum mass. You can overcome this by using compression, but that means that the Uranium/Plutonium/Whatever slug has to actually hit something (a sort of striker plate) -- and after any nuclear reaction big enough to move a ship, that striker plate isn't going to be there anymore.

On the other hand, the kind of fusion drive I brought up basically takes part of the core of a star and places it inside a magnetic field in a ship. More efficient, and continuous power. Plus, if it gets developed sufficiently, a fusion drive can actually act as a source of energy for the ship, instead of a power draw.

What about the old British Interplanetary Society's Daedalus design? That was based on igniting 'fusion microexplosions' using pellets of deuterium and helium-3 by compressing them with electron beams. Think there's any chance that such a drive system could become a reality within the next 25 to 50 years?

What about the old British Interplanetary Society's Daedalus design? That was based on igniting 'fusion microexplosions' using pellets of deuterium and helium-3 by compressing them with electron beams. Think there's any chance that such a drive system could become a reality within the next 25 to 50 years?

Hrmph. Laser/electron beam compression has been a recurring theme in fusion research. Those puppies suck energy, though, and they tend to be pretty hefty gadgets. I'd prefer a continuous fusion reaction, but the microexplosion idea could still work.

I will have to look after Merbolds concrete description and post it here but it will take a while I think.

But it was very similar to that what TJ mentions.

Concerning plutonium and uranium I didn't think of these materials as parts of a fusion drive - I only wnated to say that they are today easily might be abused as weapons and that one of the pellets TJ is talking of doesn't seem to be more dangterous. If I'm right the pellet-based fusion drive doesn't be of more threat than plutonium or uranium. (In may post I used the word "capsule" instead of "pellet" - seems to be wrong English - in german we say "Kapseln" which I translated to "capsules")

I will have to lokk after Merbolds concrete description and post ist here but it will take a while I think.

But it was very similar to that what TJ mentions.

Concerning plutonium and uranium I didN#t think of these materials as parts of a fusion drive - I only wnated to say that they are today easily might be abused as weapons and that one of the pellets TJ is talking of doesn't seem to be more dangterous. If I#M right the pellet-based fusion drive doesn't be of more threat than plutonium or uranium. (In may post I used the word "capsule" instead of "pellet" - seems to be wrong English - in german we say "Kapseln" which I translated to "capsules")

Capsule and pellet are close enough in meaning to pass here -- it's the difference between a pill and a BB. You can eat the one and shoot the other, but they're roughly the same mass.

The biggest problem I see with it is that it'd almost have to be cryogenic: I know of no other way to turn hydrogen into any sort of pellet.

I have looked for Ulrich Walter's explanation of the fusion drive I mentioned. He has worked it out a little bit in his book titled in german "Außerirdische und Astronauten" (Extraterrestrials and Astronauts) in the chapter "Interstellare Antriebe" (Interstellar Drives).

He calls it "pulsed fusion drive". The principle is to get pulses by the pieces that are the result of explosion of the very small fusionbombs.. Walter says that american experiments at Eniwetok have proven that this will be possible without damaging that portion of the spaccraft that will be impacted by the pieces. He mentions a demonstrator named "Put-Put" that has been part of the Orion project and was successful. Then he explains that Orion was terminated because of rivalries and... - the failure to close the Agreement on nuclear testing in 1963 that would have allowed usage of nuclear explosions in space as drives for peaceful space missions. The chapter contains photographs of the tests.

Furthermore he says that it was deteted that progress was to be reached by microexplosions of 1 t TNT. Then the pellets containing the fusion materials are ignited by intensive laser beams, the pieces would impact magnetic fields and pulse frequency could be increased to 100 per second. The specific pulse was increased to V(ex) = 0,03C = 9000 km/s. This concept has been proposed as the drive of Daedalus.

1 t TNT - sounds not too dangerous. As Walter explains this pulsed fusion drive is the only interesting and working concept.

To calculate the velocity 9000 km/s means 32.400.000 km/h - sufficient for travels across the solar system. But it may be that I'm misinterpreting V(ex).

i'm not sure what V(ex) means, but my guess is terminal velocity. .03C is pretty damn fast, and you have to have a propellant whose exit speed is either 1/2 or 1/4 of that (don't remember which, but it's close to one) in order to reach that speed, which is why chemical engines, even if they could carry enough fuel, can never be used for anything more than short-range missions. that speed sounds about right for a small fusion engine.

Ulrich Walter said that if Daedalus would have been built as proposed it would have been able to reach a velocity of 0,14c. It was designed for interstellar flight and would have reached Barnard's Star within less than 30 years.

From this follows that this kind of fusion drive first doesn't be usable as a weapon (this would folllow from graphics too Walter included in his book) but - more important under the aspect of space travels - second the spaceship would be able to travel everywhere in the solar system using much less pellets and laser energy because the velocity requirements are reduced.

This drive isn't revolutionary but only never built and used and it doesn't be a weapon too.

bleah you can use a butter knife as weapon, if you sharpen it well enough as we saw on 9/11, one can use an airliner as a weapon too.
anything that is large and moves can be used as a weapon.
does this mean we need to stop producing airplanes?
fire-which is what forged human civilization, originated from lightning which burned forrests and undoubtedly killed many of our ancestors.
but they figured out they can use it to cook their meals, warm and defend themselves,even though sometimes their wooden abodes burned in the process.
the same can be said about nuclear power, and, on a more esotherical level, about cloning.
let us not stop dead in our tracks because we are afraid we're gonna hurt ourselves. if we had, we'd still be living in caves eating raw meat and dying at 20.

_________________Thank you very much Mister Roboto
For helping escape when I needed most
Thank you
Thank you

bleah you can use a butter knife as weapon, if you sharpen it well enough as we saw on 9/11, one can use an airliner as a weapon too.anything that is large and moves can be used as a weapon. does this mean we need to stop producing airplanes?fire-which is what forged human civilization, originated from lightning which burned forrests and undoubtedly killed many of our ancestors.but they figured out they can use it to cook their meals, warm and defend themselves,even though sometimes their wooden abodes burned in the process.the same can be said about nuclear power, and, on a more esotherical level, about cloning.let us not stop dead in our tracks because we are afraid we're gonna hurt ourselves. if we had, we'd still be living in caves eating raw meat and dying at 20.